Molding stamper and method for fabricating same

ABSTRACT

An exemplary method for fabricating a molding stamper includes the following steps. Firstly, a master mold having microstructures spaced apart from each other is provided. Secondly, a patterned layer is formed on the microstructures, the patterned layer having molding surfaces apart from each other, and being made of a flexible organic material. Thirdly, the master mold is removed from the patterned layer. Finally, a hard coating layer is deposited on the molding surfaces to form a molding stamper.

BACKGROUND

1. Technical Field

The present disclosure relates to methods for fabricating moldingstampers, and particularly, to a method for fabricating a moldingstamper having a pattern for shaping a plurality of microlenses, and amolding stamper fabricated by the method.

2. Description of Related Art

A conventional method for making a molding stamper typically includesthe following steps: forming a photoresist layer on a substrate;exposing the photoresist layer to light, and developing the photoresistlayer using developer; etching the substrate to form a patternedsubstrate, and removing the photoresist layer; forming a seed layer onthe patterned substrate; electroforming a body on the substrate; andseparating the electroformed body from the substrate, and stripping theseed layer off the electroformed body to obtain the molding stamper.

However, this method for fabricating the molding stamper includes manysteps, and thus the production efficiency of the molding stamper israther low. In addition, portions of the seed layer may not becompletely stripped off from the electroformed body. When this happens,a surface roughness of the molding stamper is increased. This in turnmeans that the defect rate of final products made using the moldingstamper may be unduly high.

Therefore, what is needed is a new method for fabricating a moldingstamper, and a molding stamper fabricated by such method, which canovercome the limitations described.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood withreference to the following drawings. The components in the drawings arenot necessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present embodiments.Moreover, in the drawings, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is a flowchart of a method for fabricating a molding stamperaccording to an exemplary embodiment.

FIGS. 2-6 illustrate successive stages in fabricating the moldingstamper according to the method of FIG. 1.

DETAILED DESCRIPTION

Embodiments will now be described in detail below with reference to thedrawings. In this description, unless the context indicates otherwise,it is assumed that a “microstructure” is a structure which has at leastone of three dimensions thereof in the range from about 0.1 micrometersto about 999 micrometers. Similarly, unless the context indicatesotherwise, a “microlens” is assumed to have a similar meaning.

Referring to FIG. 1, a method for fabricating a molding stamper 50 (seeFIG. 6), in accordance with an exemplary embodiment, includes thefollowing steps: step S1, providing a master mold having a plurality ofspaced microstructures thereon; step S2, forming a patterned layer onthe microstructures, the patterned layer having a plurality of moldingsurfaces spaced apart from each other, and being made of a flexibleorganic material; step S3, forming a light transmissive substrate on asurface of the patterned layer, the surface being opposite to themolding surfaces; step S4, removing the master mold from the patternedlayer; and step S5, depositing a hard coating layer on the moldingsurfaces to form a molding stamper, the molding stamper comprising thelight transmissive substrate, the patterned layer, and the hard coatinglayer.

In step S1, referring also to FIG. 2, a master mold 10 is firstlyprovided. The master mold 10 includes a plurality of microstructures 101spaced apart from each other. In the present embodiment, themicrostructures 101 are made by ultra-precision cutting, and themicrostructures 101 are protrusions. In other embodiments, themicrostructures 101 may instead be made by electron beam lithography,laser lithography, particle beam lithography, etc; and themicrostructures 101 may instead be recesses.

In step S2, referring to FIG. 3, a patterned layer 20 is formed on themicrostructures 101 by pouring a flexible organic material over themicrostructures 101, and curing the flexible organic material. Thepatterned layer 20 includes a plurality of molding surfaces 201 at abottom side thereof, and a surface 202 at an opposite top side thereof.The molding surfaces 201 are spaced apart from each other, and areconfigured for shaping microlenses (not shown). The molding surfaces 201are formed by transferring the microstructures 101 onto the flexibleorganic material, and correspondingly are recesses. In the presentembodiment, the patterned layer 20 is made of polydimethyl siloxane(PDMS). In alternative embodiments, the molding surfaces 201 may insteadbe protrusions. In other alternative embodiments, the patterned layer 20may instead be made of polymethyl methacrylate (PMMA), polycarbonate(PC), etc.

In step S3, referring to FIG. 4, a light transmissive substrate 30 isformed on the surface 202 of the patterned layer 20. The lighttransmissive substrate 30 is configured for supporting the patternedlayer 20 to facilitate a higher bearing strength of the mold stamper 50.

In step S4, referring to FIG. 5, the master mold 10 is removed from thepatterned layer 20.

In step S5, referring to FIG. 6, a hard coating layer 40 is deposited onthe molding surfaces 201 and on a bottom surface of the patterned layer20 that surrounds the molding surfaces 201, thereby forming the moldingstamper 50. The molding stamper 50 includes the patterned layer 20, thelight transmissive substrate 30, and the hard coating layer 40. The hardcoating layer 40 is configured for enhancing the hardness of the moldingsurfaces 201. In the present embodiment, the hard coating layer 40 isdeposited by radio frequency magnetron sputtering, and the hard coatinglayer 40 is made of silicon dioxide. In other embodiments, the hardcoating layer 40 may instead be made of silicon, silicon carbide,diamond-like carbon, etc.

When the hard coating layer 40 is being deposited, a bombardmenttemperature on a silicon dioxide sputtering target (not shown) is in arange from about 160 degrees Centigrade to about 200 degrees Centigrade.A pressure in a vacuum cavity (not shown) receiving the combinedpatterned layer 20 and light transmissive substrate 30 therein is in arange from about 0.013332 pascal (Pa) to about 0.13332 Pa. The vacuumcavity is preferably held at room temperature for preventing the moldingsurfaces 201 from deforming.

Because the molding stamper 50 is fabricated by the transfer imprint ofthe master mold 10, the method for fabricating the molding stamper 50 issimple, thereby enhancing the production efficiency of the moldingstamper 50. In addition, the method for fabricating the molding stamper50 does not require removal of any seed layer from the molding surfaces201. Thus surface roughness problems associated with conventionalmolding stampers are circumvented. Furthermore, the hard coating layer40 can enhance the hardness of the molding surfaces 20. Accordingly, themolding stamper 50 has a higher wear resistance.

In alternative embodiments, step S3 may instead be performed after stepS4 and before step S5. In other alternative embodiments, step S3 mayinstead be performed after step S5. In still other alternativeembodiments, the step S3 may instead be omitted.

While certain embodiments have been described and exemplified above,various other embodiments will be apparent to those skilled in the artfrom the foregoing disclosure. The disclosure is not limited to theparticular embodiments described and exemplified, but is capable ofconsiderable variation and modification without departure from the scopeand spirit of the appended claims.

1. A method for fabricating a molding stamper, the method comprising:providing a master mold having a plurality of microstructures thereon,the microstructures spaced apart from each other; forming a patternedlayer on the microstructures, the patterned layer having a plurality ofmolding surfaces spaced apart from each other, and being made offlexible organic material; removing the master mold from the patternedlayer; and depositing a hard coating layer on the molding surfaces toform a molding stamper.
 2. The method of claim 1, wherein themicrostructures of the master mold are made by a method selected fromthe group consisting of ultra-precision cutting, electron beamlithography, laser lithography and particle beam lithography.
 3. Themethod of claim 1, wherein the hard coating layer is deposited by radiofrequency magnetron sputtering.
 4. The method of claim 3, wherein thehard coating layer is comprised material selected from the groupconsisting of silicon dioxide, silicon, silicon carbide and diamond-likecarbon.
 5. The method of claim 4, wherein the hard coating layer iscomprised of silicon dioxide, and during the depositing of the hardcoating layer, a bombardment temperature on a silicon dioxide sputteringtarget is in a range from 160 degrees Centigrade to 200 degreesCentigrade, a pressure in a vacuum cavity receiving the patterned layertherein is in a range from 0.013332 Pa to 0.13332 Pa, and the vacuumcavity is at room temperature.
 6. The method of claim 1, furthercomprising forming a light transmissive substrate on a surface of thepatterned layer, the surface being on a side of the patterned layeropposite to the side of the patterned layer having the molding surfaces.7. A molding stamper comprising: a patterned layer, the patterned layercomprising a plurality of molding surfaces at one side thereof and asurface at an opposite side thereof, the molding surfaces being spacedapart from each other, the patterned layer being made of flexibleorganic material; a light transmissive substrate attached to the surfaceof the patterned layer; and a hard coating layer deposited on themolding surfaces.
 8. The molding stamper of claim 7, wherein theflexible organic material is comprised of material selected from thegroup consisting of polydimethyl siloxane (PDMS), polymethylmethacrylate (PMMA) and polycarbonate (PC).
 9. The molding stamper ofclaim 7, wherein the hard coating layer is comprised of materialselected from the group consisting of silicon dioxide, silicon, siliconcarbide and diamond-like carbon.
 10. A molding stamper comprising: apatterned layer, the patterned layer comprising a plurality of moldingsurfaces spaced apart from each other, the patterned layer being made offlexible organic material; and a hard coating layer deposited on themolding surfaces.
 11. The molding stamper of claim 10, wherein theflexible organic material is comprised of material selected from thegroup consisting of polydimethyl siloxane (PDMS), polymethylmethacrylate (PMMA) and polycarbonate (PC).
 12. The molding stamper ofclaim 10, wherein the hard coating layer is comprised of materialselected from the group consisting of silicon dioxide, silicon, siliconcarbide and diamond-like carbon.